In Digital Light Processing (DLP) projectors, light is generated from a single source and reflected by a digital micro-mirror device (DMD) which comprises an array of controllable micro-mirrors. Using this principle, the light rays are created with controllable intensity. The micro-mirrors digitally switch the light rays through or away from the lens at a high frequency, so the intensity of the light can be changed in small steps.
A spot dot lamp (otherwise known as a pixelated spot lamp, or a matrix spotlight) can be considered as a lamp that creates a plurality of small “spots”, similar to the projectors that use DMD devices. In a spot dot lamp, the functionality of the DMD for creating a matrix of light pixels is replaced by a light-emitting diode (LED) matrix of controllable LEDs (referred to as spot dots) and optics to collimate the light rays emitted by the LEDs. By switching the individual LEDs in the matrix, the light pattern generated by the spot dot lamp is controllable.
Spot dot lamps can be configured to provide any desired beam shape due to the ability for a user to individually control the light emitted from each of the LEDs, but the desired shape needs to be communicated to the lamp in some way.
In the current state of the art, the resolution of DMD devices is in the megapixel range while spot dot lamps are under the 100 pixel range, with advances in technology there is scope for this to increase.